Analysis of workload of tank crew under the conditions of informatization

Ming MAO*,Fang XIE,Jian-jun HU,Bo SU

China North Vehicle Research Institute,Beijing 100072,China

Analysis of workload of tank crew under the conditions of informatization

Ming MAO*,Fang XIE,Jian-jun HU,Bo SU

China North Vehicle Research Institute,Beijing 100072,China

A consensus has been reached that the tanks need to be integrated into the informatization battlefeld.With the development of technology, the tank crew has being gradually decreased,so the research on two-soldier crew tank has become a hotspot.The workload of tank crew under the conditions of informatization is analyzed based on the combat mission of tank and the typical combat scenarios,and the impact of new technologies on workload is evaluated.The crew members in tank can be reduced from three to two,but it is necessary to substantially improve the automation of target search and the reliability of each subsystem and component.

Tank;Human factor engineering;Two-soldier crew;Workload

1.Introduction

The main battle tank crew has been reduced from fve crew members(commander,gunner,loader,driver and co-driver)in World War II(such as Germany’s Tiger)to three or four crew members.The third generation main battle tanks of China, Russia and France are operated by three tank crew members (commander,gunner and driver),while United States’M1A2 and Germany’s Leopard 2A7+are operated by four crew members[1].

Many countries are developing new tanks or upgrading the active tanks[1]so that the tanks can be integrated into the informatization battlefeld,and has the capability to participate in the integrated joint operation.With the development of automation and intelligent technologies,new main battle tank operated by two-soldier crew has become possible.According to calculation,one crew member needs to occupy an interior space of 1.0-1.7 m3.The operation of two-soldier crew members favors to reduce the combat weight and height of tank.Moreover,the distribution of two soldier crew tank is centralized in compartment that can isolate the crew module, combat room and engine compartment effciently to improve the ability of anti-quadratic effect,cooperative operation and continuous combat,favor the optimization of human-machine interaction interface,and implement the integrated control of crew environment.Besides,the crew members can see and talk to each other directly in the tank to ease their intense sentiments and improve the communication effciency of the crew members and their continuous operational capabilities.United States mainly research the two-soldier crew solution[2]for the manned combat vehicle in Future combat systems(FCS)[3]. Israel raised a New tank developing project in 2012.The main features of the tank which is operated by two crew members are to use hybrid drive,laser weapon or electromagnetic pulse cannon[4].Russia also raised a development concept of twosoldier crew tank recently.So far,there has been no twosoldier crew tank in the world.

The endurance of crew,the operating accuracy,and the reduction of the physical and chemical harmful effects in the operating environment were only considered in the design of frst generation tank during World War II.From the middle to the end of last century,in the design of the second and thirdgeneration tanks,the crew and the tank must be optimized as a system,and they must mutually‘adapt’.After the entry of the 21st century,with the development of information technology, the operation mode and human-machine interaction(a.k.a human computer interface)of tank have undergone a revolutionary change,and the old mechanical system characterized by‘hand and foot control,and display of the physical parameters on instrument’has been developed into an‘Information system’ human-machine computer interface characterized by‘multi-mode control and integrated information display’.The concept of human factor engineering has been widely introduced in the design of tanks and armored vehicles in United States and other developed countries,which is basically the same as human-machine engineering and ergonomics.‘Information system’human-machine interface has brought a revolutionary change to the workload of crew members,from the‘manual workload’in mechanical system to‘mental workload’in information system.

In the paper,the workload of tank crew is analyzed,and the effect of new technology on workload is investigated according to the combat mission of tank and the typical combat scenariosundertheconditionsofinformatization.The research purpose is to provide the technical support to the top level design of tank,information system,crew module and other subsystems,and design of units,such as display and control terminal.

2.Combat missions and scenarios of tanks under the conditions of informatization

Tank,as a ground frontline assault weapon with mobility, combat ability and shielding,is capable to fght with any hostile armored target,frm bastion,or effective strength,and fre against the air targets.It can receive,perceive,process and transmit any battlefeld information in real time,and cooperate with other armed services in the battlefeld.

2.1.Combat mission and basic tactical action of tank

The combat mission of tanks is variety.Their mission profle can be generally divided into combat preparation, changing from traveling to fring positions and concentration, hiding and reconnaissance,combat,maintenance and supply, and training.The combat mission,however,is the main duty of tank,as well as the typical task of tank crew.Hence,the combat mission is taken as the main object of study here.

The combat can be divided into attack and defense modes for different tactics.The tank tactics consist of maneuver, battlefeld observation and target search,target destruction, battlefeld protection,cooperation in and outside vehicle,etc.

Maneuver is to drive a vehicle.The most complex operating condition is to maintain the cooperation in and outside vehicle(maintaining the formation,and moving forward to a designated terrain such as hidden objects,or passing through a mine feld cleared by engineer)when facing enemy fre or even strike under the circumstance of insecurity road and complex terrain.

Battlefeld observation and target search is to utilize vision or electro-optical system(perception system)to monitor, observe and search the targets.The typical operating condition is motionless covert observation and surveillance to mark the discovered main landmarks and targets.The most complex operating condition is to search the random targets and judge their properties during maneuvering.

Target destruction is to utilize fre control system to identify,track and aim at target,set the fring data and load the corresponding ammo,and use a lethal fre to destroy the targets.The targets include those designated by higher command and those found in advance or real time by crew.The typical work condition is to continually judge,make a decision and destroy the targets,at the same time keep the cooperation in and outside vehicle closely.

Battlefeld protection is to use the electro-optical information warfare system to warn,the electro-optical or electronic countermeasures(such as,suppression of enemy surveillance, range fnding and aiming,interference,and decoy),evasive maneuver,smoke screen,or to destroy the incoming ammo. The typical operating condition is to move quickly to advantage terrain or safe zone covered by smoke screen,as well as keep the close cooperation and wage the electro-optical information warfare.

The cooperation outside vehicle is to implement the communication between crew members,basically the commander,and keep coordination,such as speed and course control during aiming and tracking of target).The typical operating condition is that the commander designates a target and the mobile direction,and gives the fring command during moving.

The cooperation outside vehicle is mainly to receive the information,such as battlefeld situation,geographic and meteorological information,combat mission,combat zone, combat command,combat signal,hostile target location and attributions,from superior;deliver the battlefeld report(the situations enemy and friendly force);ask for support(fre support,emergency maintenance support);cooperate closely with neighboring tanks,infantry fghting vehicles,infantry,or even attack helicopters.The typical operating condition is to keep formation with neighboring tanks to travel and cooperate closely to destroy target.

2.2.Combat scenario

United States Army Research Laboratory(ARL)divided the combat mission profle of manned combat vehicle into combat scenario,automated search scenario,combat with no engagement scenario and non-combat scenario in the development of the Future Combat Systems,and set 10 min typical mission scenario for the four combat situations,respectively. All of these scenarios only contain the information exchange between crew members or between commanders and superior command systems.

When the Research and Development Division of Canadian Department of National Defense developed the advanced land fre control system(ALFCS)with automatic target detectionand tracking system(ATD&T)as the core,the division set two 15 min typical mission scenarios:static observation and search scenario and combat scenario.The core of static observation and search scenario is that 18 targets randomly appear at the distance of 500-3500 m.This targets include friendly force targets and enemy targets which are fully exposed and partly exposed(50%and 25%).The core of the combat scenario is that 8 static or moving targets randomly appear at the distance of 1000-2200 m,and the vehicle searches,tracks,aims and fres at the target during moving.

Target destruction is the most typical one in basic tactical operations in which with the mental workload of crew members is the heaviest.It can signifcantly refect the characteristics of the most frequently human-machine interaction under the conditions of informatization.Therefore,target destruction will be a combat scenario in the research.When the scenario is set,the following principles should be followed:

1)Full coverage of task

The set scenario should include all of the functions and performance of tank in the task profle.

2)Randomness of task

Targets,superior instructions,battlefeld environment and situation should change randomly.

Based on the principles,the scenario of target destruction in the research is set as:the tanks are ready for combat when hiding,and the locations of two static hostile concrete fortifcation targets and two mobile armored targets are determined;when the commander receives the assault command from company commander,four mobile hostile tanks and two infantry fghting vehicles will appear in the battlefeld randomly.The commander must report the enemy’s situation, damage situation of enemy targets and serious damage situation of friendly force tanks(such as tanks’loss of mobility, combat capability and casualties)to company commander in real time.He can also instruct the driving direction or speed, observe the battlefeld,search the targets,fnd and mark the armored target,and then report to company commander in command tank.

The combat scenario does not contain the setting of geographical environment in battlefeld.It is because that the geographical environment mainly affects the workload of driver.According to research,the main task of driver in twosoldier crew tank is to drive the tank,so the workload of driver changes a little.

3.Workload analysis of tank crew

United States Army used Improved Performance Research Integration Tool(IMPRINT)to measure the workload of tank crew.IMPRINT was developed based on the Multiple Resource Theory(MRT)which was proposed by Wickens[2]. In MRT,it is considered that the mental resource which is used to receive and process information and react is limited.For example,a person can hardly watch two screens simultaneously,because he has limited vision resource.If he has to watch two screens at the same time,the grasp degree of informations which he obtains from two screens is less than that which he obtains from one screen.That is to say,his working effciency will be discounted.

IMPRINT divides human physiological resources into vision,auditory sensation,cognition and psychomotor,which is the VACP model.For each physiological resource,the load has seven levels with specifc metrics.When a resource load is over 7,it is excessive so that the working effciency of human reduces.Similarly,if the total load of four physiological resources for one task is over 28,then it can be considered that it exceeds the limit of human workload.

3.1.Workload analysis of crew in Al-Khalid tank

The workload of crew in Al-Khalid tank is calculated using the workload rating system based on IMPRINT(seeing Table 1).

It can be seen from Table 1 that the workloads of commander and driver are heavy,and their total workloads exceed 28-A crew member should endure the maximum workload in combat.In the process of fring on move,the driver needs to control the direction of tank,look at the forward terrain,keep the speed and driving direction tank,communicate with the commander and monitor the instruments at the same time.On the other hand,the workloads of commander’s cognition and psychomotor are heavy,while the workload of vision is light; for the driver,the workloads of vision and cognition are heavy, while the workload of auditory sensation is light.

3.2.Workload of crew in United States M1A2SEP V2 tank

The United States M1A2SEP V2 is the newest version of M1A2.It integrates the System Enhancement Package(SEP), a.k.a the Army’s Force XXI command and control system and the new technology achievements which were spirally developed from FCS.The maximum workload of each crew member is calculated based on the VACP model from IMPRINT,as listed in Table 2.

It can be seen from Table 2 that the workloads of commander and driver are heavy,too,and their limit workloads exceed 28.The heavy workload of commander concentrates in monitoring the battlefeld,searching the targets,marking the situation map,and keeping communication with superior commanders and crew and cooperation.The workload of commander’s cognition and auditory sensation is heavy. Driver endures the same maximum workload as in Al-Khalid tank,while M1A2SEP V2 tank has the ability to keep speed and driving direction.The workload of driver’s vision and cognition is heavy.The workload of his auditory sensation, however,is 0.It is because that communication while driving will probably increase the workload of driver,and decrease the driving effciency.The maximum workloads of gunner and loader are the same,and are signifcantly lower than those ofcommander and driver,but their cognition workloads are relatively heavy.Hence,gunner and loader can assist commander to undertake the task of monitoring the battlefeld and searching the targets.So the commander can focus on communication and command.

Table 1Maximum workload of crew of Al-Khalid tank.

Table 2Maximum workload of crew of M1A2SEP V2 tank.

3.3.Workload analysis of crew in two-soldier crew tank and discussion of new technologies and their applications

On the basis of the above analysis and calculation,the workload of tank crew is heavy during combat mission, especially for commander and driver.If the crew members are reduced to two,it will be diffcult to fnish the combat mission without the new technologies.On the other hand,one crew member is required to drive the two-soldier crew tank,the tasks,such as command,battlefeld surveillance,target search and fring,must be completed by another member.The maximum workload of the crew in FCS two-soldier crew manned combat vehicle[4]is calculated based on the VACP model from IMPRINT,as shown in Table 3.

It can be seen from Table 3 that,compared with M1A2SEP V2,the workload of crew increases considerably because of the increased workloads of vision and psychomotor.The main reason is the increase in management task of situation map and the reduction of crew members.

It also shows that the workload of crew members in twosoldier crew tank is heavier than that in three-soldier crew tank.So the workload of crew members needs to be reduced by introducing the new technologies,and should not be higherthan that in three-soldier crew tank at least;in other hand,the new functions,such as air surveillance,electro-optical countermeasures,electronic countermeasure and hard intercept ammo,must be automated.

Table 3Maximum workload of crew in FCS two-soldier crew manned combat vehicle.

Table 4VACP workload of two-soldier crew in combat mode with new technologies.

The measures to reduce the workload of crew members include automatic target search,attributive judgment and automatic tracking;automatic calibration,one-button start, auxiliary driving(cruise,course keeping and obstacle avoidance);text-to-sound(TTS);situationmapautoupdating,combat message auto-generation,etc.After introducing the new technologies,the workload of crew members in combat mode is calculatedandanalyzedbasedonIMPRINT,aslistedinTable4.

It can be seen from Table 4 that the workload of crew members decreases signifcantly after introducing those new technologies.Of course,the calculated results depend on each system in normal operating condition.If the system does not work properly with the high probability of false alarm,the workload of crew members,especially the psychomotor workload,will increase dramatically.

4.Conclusion

The crew members in tank can be reduced from three to two;one must function as a driver,and the other needs to undertake the combat mission,namely performing the command and fring tasks.In order to reduce the workload of gunner/commander,it is necessary to substantially improve the automation of target search and the reliability of each subsystem and component.The IMPRINT predicted workload of crew member,as a reference value,can be used to evaluate the impact of recommended technologies on the workload and effciency of crew members.When a new technology is introduced in tank,the workload of basic model should be not only maintained or reduced,but also the operation effciency of crew member,i.e.the effciency of human-machine interaction,should be kept or improved.

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[2]Mitchell DK.Workload analysis of the crew of the Abrams V2 SEP:phase I baseline IMPRINT model.ARL-TR-5028;2009.pp.49-69.

[3]Mitchell DK,Samms CL,Henthorn T.Trade Study:a two-versus threesoldier crew for the mounted combat system and other future combat system platforms.ARL-TR-3026;2003.pp.87-102.

[4]Editorial Board of Foreign Tank.The major event of armored equipments for 2012.For Tank 2013:40-2.

Received 23 July 2013; revised 16Oc tober 2013; accepted 12November 2013 Availab leon line3 January 2014

*Corresponding author.

E-mail address:ming_mao@noveri.com.cn(M.MAO).

Peer review under responsibility of China Ordnance Society.

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http://dx.doi.org/10.1016/j.dt.2013.12.008

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